largefiles: use readasstandin() to read hex hash directly from filectx BTW, C implementation of hexdigest() for SHA-1/256/512 returns hex hash in lower case, and doctest in Python standard hashlib assumes that, too. But it isn't explicitly described in API document or so. Therefore, we can't assume that hexdigest() always returns hex hash in lower case, for any hash algorithms, on any Python runtimes and versions. From point of view of that, it is reasonable for portability that 40800668e019 applies lower() on hex hash in overridefilemerge(). But on the other hand, in largefiles extension, there are still many code paths comparing between hex hashes or storing hex hash into standin file, without lower(). Switching to hash algorithm other than SHA-1 may be good chance to clarify our policy about hexdigest()-ed hash value string. - assume that hexdigest() always returns hex hash in lower case, or - apply lower() on hex hash in appropriate layers to ensure lower-case-ness of it for portability